英文:
Redis unlink hash - is the hash treated as a whole or not?
问题
在Redis中，哈希表的情况如下：
ha -> {
k1 -> v1
k2 -> v2
k3 -> v3
}
当执行unlink ha时，Redis会如何实际删除它？
我能想到的可能方式：
- A. 首先删除单个键
ha，然后稍后在另一个线程中将整个值（包括3个子键）作为一个整体删除。 - B. 删除键
ha，以及子键k1、k2、k3。然后稍后删除子键的3个值？
那么是哪种情况，或者还有其他方式？
根据上述代码，似乎更像是情况B。这是有道理的，因为哈希表存储对值的引用，而不是在单个内存块中，因此需要逐个释放值，对吗？
相关的Redis源代码
https://github.com/redis/redis/blob/3ca451c46fed894bf49e7561fa0282d2583f1c06/src/dict.c#L553
英文:
e.g:
In redis, the hash is:
ha -> {
k1 -> v1
k2 -> v2
k3 -> v3
}
When unlink ha, how would redis actually delete it?
(assume values of the 3 sub keys are large enough to make redis decide to remove them in a separate thread).
The possible ways I can image:
- A. Remove single key
ha, then later remove the whole value (with 3 sub keys) as a whole, in another thread. - B. Remove key
ha, and sub keysk1,k2,k3. Then later remove the 3 values of the sub keys?
So which is the case, or there are more ways?
Relevant redis source code
https://github.com/redis/redis/blob/3ca451c46fed894bf49e7561fa0282d2583f1c06/src/dict.c#L553
According to the code above, seems it's more like case B.
That make sense, since hashtable store reference to value, not in a single memory block, thus need to free the values 1 by 1, right ?
答案1
得分: 3
当调用unlink来移除一个键（哈希或其他结构）时，Redis会逻辑上删除它，从数据库中移除它（键、子键和值），并将其放入待删除列表。会有一个后台任务在另一个线程中懒惰地删除这些已被移除的项目。当Redis执行真正的删除工作时，它会删除与该键有关的所有内容（键、子键和值）。
英文:
When you call unlink to remove a key (hash or any other structure), Redis deletes it logically by removing it (key, sub key, and value) from the DB, and putting it into a to-be-deleted list. There will be a background job that deletes these lazily removed items from another thread. When Redis does the real delete job, it delete everything about the key (key, sub key, and value).
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